摘要
强人类活动目前已经成为河口演变的主要动力。阐明流量驱动下河控型河口潮波传播演变过程及机制,对河口治理及人类活动的影响评价具有重要指导意义。以珠江磨刀门河口为例,研究了径潮动力阶段性演变特征。采用流量驱动的R_TIDE数据驱动模型探究了该区潮波振幅梯度和上下游动力边界(即上游流量和口门振幅)关系的变化规律。结果表明,在强人类活动影响下,各潮位站M_(2)分潮振幅明显上升(三灶站除外),且具有季节性差异和阶段性变化,灯笼山-马口河段的M_(2)分潮振幅沿程平均增大约0.07m,河段潮波振幅梯度平均增大约4.61×10^(-6)m^(-1)。研究潮波振幅梯度与上下游动力边界的阈值的关系表明,阈值效应主要出现在甘竹-马口河段。在强人类活动影响下,潮波振幅梯度阈值增大,相应的流量阈值增大,而振幅阈值基本不变。在达到振幅阈值之前,由于底床摩擦效应,大潮振幅衰减效应大于小潮,而在超过振幅阈值后,地形辐聚效应成为影响潮波振幅梯度变化的主要因素,大潮振幅衰减效应小于小潮。阈值的变化主要与流量、地形、摩擦等多因子耦合作用有关,当地形辐聚效应和底床摩擦效应达到平衡时,潮波振幅梯度与上下游动力边界之间则出现阈值效应。该现象的发现可为河口海岸防灾减灾和水资源管理等实际问题提供重要理论支撑。
Recent strong human activities have become a considerable driving force of estuarine evolution.Understanding the evolution and mechanism of tidal wave propagation in an estuary shall have important significance for estuarine governance and human impact assessment. Taking Modaomen estuary of the Zhujiang(Pearl) River as an example, the stepwise evolution characteristics of river-tide dynamics were studied. A data-driven R_Tide model was used to explore the variation law of the relationship between tidal wave amplitude gradient and upstream and downstream dynamic boundary(i.e. upstream river flow and portal tidal amplitude). The results show that under the influence of strong human activities, the M_(2)tidal amplitude of each tidal gauging station increases significantly(except for Sanzao station),and has seasonal differences and periodic changes. The average increase along Denglongshan-Makou sector is about 0.07 m, and the average increase of tidal wave amplitude gradient along river channel is about 4.61×10^(-6)m^(-1). Relationship between the amplitude gradient of tidal wave and the threshold of upstream and downstream dynamic boundary shows that the threshold effect occurs in Ganzhu-Makou sector mainly. Under the impact of strong human activities, the amplitude gradient threshold of tidal wave increases, the corresponding river discharge increases, while the corresponding tidal amplitude remains largely unchanged. Before the amplitude threshold, the amplitude attenuation effect of spring tide is greater than that of neap tide due to the river-bed bottom friction. After exceeding the amplitude threshold, the geometric convergence becomes the main factor affecting the variation of tidal wave amplitude gradient, and the amplitude attenuation effect of spring tide is less than that of neap tide. The change of the threshold is mainly related to the coupling effect of multi-factors such as river discharge, geometry, and friction. When the geometric convergence and river-bed bottom friction is balanced, the threshold effect appears between the tidal wave amplitude gradient and the upstream and downstream dynamic boundary. Understand such a phenomenon will provide a crucial theoretical support for practical applications such as disaster prevention and mitigation as well as water resources management in general.
作者
李博
杨昊
欧素英
蔡华阳
刘锋
杨清书
LI Bo;YANG Hao;OU Su-Ying;CAI Hua-Yang;LIU Feng;YANG Qing-Shu(Institute of Estuarine and Coastal Research,School of Ocean Engineering and Technology,Sun Yat-sen University,Guangzhou 510275,China;State and Local Joint Engineering Laboratory of Estuarine Hydraulic Technology,Guangzhou 510275,China;Guangdong Provincial Engineering Research Center of Coasts,Islands and Reefs,Guangzhou 510275,China;Southern Laboratory of Ocean Science and Engineering(Zhuhai),Zhuhai 519000,China)
出处
《海洋与湖沼》
CAS
CSCD
北大核心
2022年第3期513-527,共15页
Oceanologia Et Limnologia Sinica
基金
国家自然科学基金项目,51979296号
广州市科技计划项目,202002030452号。
关键词
河口径潮动力
R_TIDE数据驱动模型
人类活动
余水位梯度
阈值效应
estuarine river-tide dynamics
R_TIDE data-driven model
intensive human interventions
residual water level gradient
threshold effect
